Composition and process for demulsifying cut oils and the like



Patented Aug. 18, 1936 PATENT OFFICE COMPOSITION AND PROCESS FOR DEMUL-SIFYING CUT OILS AND THE LIKE Harold Jay Robertson, Tulsa, Okla.,assignor to Sinclair Refining Company, New York, N. Y.,

a corporation of Maine No Drawing. Application December 12, 1934, SerialNo. 757.215

12 Claims.

My invention relates to the treatment of emulsions of water in oil forthe purpose of separating the water therefrom.

In the operation ofoil wells, in addition to the crude oil obtained,there is ordinarily produced a greater or lesser proportion of cut oil"or bottom settling, this being an emulsion of water or brine in the formof fine droplets dispersed through the oil which constitutes thecontinuous phase of the emulsion, the emulsion being more or lesspermanent, unless treated for the removal of the water.

It has long been known that many such cut oils may be more or lesseffectively resolved or separated into oiland water by the use ofsoftening agents such as soluble soap, etc. The usually accepted theoryof these emulsions and their resolution by water softening agents isthat the water of the droplets is surrounded by a skin or layercontaining an emulsifying agent, the precise nature of which is notclearly known, which holds the droplets in suspension in the oil; andthat the water softening agent dissolving in the water or brine of thedroplets neutralizes or opposes the effect of the emulsifying agent,thus freeing the water and permitting it to drop out of the oil.

Cut oils from different wells and regions vary in their stability ofemulsion and many of them are but little, if at all afiected bytreatment with the usual water softening agents. I believe that this isdue to the character of the interface or envelope between the water orbrine of the droplets and the continuous oil phase, because of which thewater softening agent in the case of some out oils more readilypenetrates to the water of the dispersed phase, while in the case ofother cut oils access of the water softening agent to the water isopposed or altogether prevented by the character of the envelopingemulsifying agent.

Whether this difference in penetrability of the interfacial layers ofemulsifying agents is due to differences in chemical composition or tophysical differences such as in surface tension, thickness of theinterfacial layer, size of droplets, or the like, I am unable to say.

In my improved demulsifying composition I provide a reagent, in additionto the water softening agent, which appears to aid the water softeningagent in penetrating the emulsifying layer or 5 envelope or indissipating the latter, permitting the Water softening agent to obtainaccess to the water or brine of the droplets. Whether or not theforegoing theory correctly represents the phe-* nomena in question, Ihave found in practice that 55 by the addition of compounds of the classhereinafter mentioned to the watersoftening agents, the latter arerendered more effective in demulsifying the cut or oily oils and areeffective in demulsifying many such cut oils which are but slightlyresolved or not at all by the water soften- 5 ing agents in the absenceof such compound. The compounds to which I have just referredaaassistingthe demulsifying action of water softening compounds are the alkalihydrogen sulfite addition compounds of the aldehydes and ketones. 1"Among the more commonly known aldehydesand ketones which form alkalihydrogen sulflte addition compounds which may be used in the practice ofmy invention are butyl aldehyde, crotonaldehyde, aldol, benzaldehyde,furfurai, acetone, methyl-ethyl ketone and methyl iso-butyl ketone, allof which are relatively inexpensive and can be readily obtained on themarket. I have found that the alkali hydrogen sulfite reaction productsof. each and any of these aldehydes and 2 ketones., when mixed withsoap, soap and fatty materials, or other water softening compounds ofthe kind, produce excellent demulsifying agents, which are moreeflicient in treating many out oils than the water softening agents when25 used alone.

In addition to the soluble soap or similar water softening agent and theabove mentioned reagents for facilitating the action of the watersoftening agent, my improved water softening compound 30 may containalso a flxed oil, suchas castor oil.

Inasmuch as liquid reagents are more suitable for use in the field,especially where they are fed into the flow line from the well to thewash or settling tank as is now customary, I prefer to 35 use a liquidsoap in my composition such as a soap of ricinoleic acid, though thesoaps of other acids may be used, and for a portion of the fatty acidsoap, a rosin may be substituted. It is also preferred to use anammonium soap, because of its superior fluidity, rather than a sodium orpotassium soap, though either of the latter may be used. However, withthe use of semi-solid and solid soaps, the compositions formed rangefrom semi-solid to solid and require in mos... cases special means ofhandling at the well (but which are now well known) and also specialcontainers, instead of the ordinary steel drums used for liquidreagents, thus causing considerable inconvenience and extra expensewhich is obviated by the use of a liquid composition. For like reasons,when fatty ingredients are employed, low cold test fixed oils, such ascastoroil or oils from which the solid fats have been eliminated, are tobe preferred. However non-liquid as wellv as liquid 55 reagents areeflicient in breaking petroleum emulsions and can be used in thepractice of my invention with the proper known devices for measuring andfeeding the reagent into the cut oils to be treated.

The water softening agent may be prepared in any known or obviousmanner. I prefer, however, the following process and preparation: Thefatty acids, (and in case rosin is used to make part of the soap, therosin) are introduced into an ordinary mixing kettle. If fatty mattersuch as castor oil or other low cold test fixed oil is to be introducedinto the compound, this also is added to the contents of the kettle,particu larly as it tends to prevent a too violent reaction when thealkali is added to the fatty acid. Then the alkali is slowly added withconstant stirring of the mass. If, as preferred, an ammonium soap is tobe formed, strong ammonium hy'droxid (preferably the commercial 26 B.aqua ammonia) is added, the mixture being cooled if necessary, as attemperatures in excess of 100 degrees F., there is considerable loss ofammonia by evaporation. The strong ammonia is used in order to keep thewater content of the mix as low as possible, as too much water causes atendency to jell. If, as is sometimes desirable, the demulsifying agentwhen completed is to be basic, I suitably increase the amount of ammoniaused above that necessary merely to form the soap. Otherwise, theammonia should be added in the quantity necessary to neutralize theacids. After the lngredients including the ammonia have been added themixture is preferably allowed to remain quiet to insure completion ofthe soap reaction, usually from two to three hours or over night ifconvenient.

The aldehyde or ketone hydrogen sulfite ingredient may be prepared inany usual or known manner, but preferably as follows:

A suitable amount of sodium or other alkali bisulfite is dissolved inwater to form a cold saturated solution. To this solution is then addedgradually the selected ketone 01 aldehyde or a mixture of ketones oraldehydes or of both, in amounts sufficient to react with all of thebisulfite used. If the reaction product is soluble in water, it may bedesirable to add more water than stated above to keep the reactionproduct in solution. If, however, the reaction product is insoluble orsoluble with difliculty in water, as in the case of benzaldehyde alkalihydrogen sulfite,- it will, of course, be precipitated and in this eventthe water may be removed by filtering and drying and the hydrogensulfite compound then dissolved in the soap solution in the proportionby weight desired. If the hydrogen sulfite compound is not readilysoluble in the soap, its solution may be expedited by the addition of asmall quantity of a suitable solvent, such as commercial alcohol, to themixture. Also, if desired, the filtration and drying steps may beomitted, and the mixture of hydrogen sulfite compound and the excesswater added to the soap solution, together with sufficient alcohol orother solvent, if necessary, to afford complete mixability with thesoap. I have found 'it preferable to use sumcient aldehyde or ketone tocompletely combine with the sulfite salt. Excess sulfite salt in thedemulsifying agent seems to have a tendency to cause the emulsion tosludge down without the desired water separation, but a slight excess ofaldehyde or ketone appears not to cause any harmful effect in thetreatment of the emulsion- A specific example of the preparation of thesulfite ingredient, in this case furfural potassium hydrogen sulfitesolution, is as follows:

20 parts by weight .of potassium meta bi-sulflte (containing 56.4%available $02) in granulated form, is dissolved in 38 parts by weight ofwater, heating slightly to get complete solution of the salt. To thissolution, after cooling, is added slowly with stirring 21.8 parts byweight of furfural. (technical, 97%), cooling when necessary to preventtoo rapid rise in temperature. The amount of furfural required iscalculated from the available S02 in the bi-sulflte and the purity ofthe furfural, which latter is determined by chemical tests.

The water softening material, prepared as above described, or otherwise,and the aldehyde or ketone hydrogen sulfite product prepared as abovedescribed or otherwise, are thoroughly mixed together to insure ahomogeneous, substantially clear mixture of the various ingredients.

A specific example of a demulsifying agent embodying my invention whichI have successfully used has substantially the following percentagecomposition This composition was prepared in substantially the mannerspecifically described above, the materials used and their proportion byvolume being substantially as follows:

Furfural potassium hydrogen sulfite solution (prepared as abovedescribed) 11.1

' Ricinoleic acid 50.4 Aqua ammonia (26 B.) 8.9 Castor oil- 29.6

It will be understood that the water softening composition was preparedin the manner previously described herein from the ricinoleic acid,ammonia and castor oil in the proportions given, and the furfuralpotassium hydrogen sulfite solution prepared as described, and thenadded to the water softening compound in the proportion given in theabove tabulation.

The amount of my demulsifying compound to be used in proportion to theamount of emulsion treated varies somewhat depending upon the characterof the cut oil. In various field tests on different cut oils 1 have usedone gallon of the compound to treat from about 250 barrels of cut oil toabout 400 barrels of the same with excellent results. In a specificinstance 1108 barrels of clear, marketable petroleum were produced froma cut oil, with no bottom sediment discernible in either the washing orsettling tank with 4 gallons of the demulsifying compound, correspondingto an average of 246 barrels produced per gallon of treating agentemployed, or less than one part of compound to ten thousand gallons ofoil produced, though the same cut oil tested with the same watersoftening compound but in the absence of the sulfite addition showed nosubstantial effect.

As previously stated, cut oils, bottom settlings and the like differconsiderably among themselves and I have found it desirable therefore tovary the specific proportions of ingredients given in the abovetabulation. Also, in some instances the treating agent is more effectiveif basic in reaction, and with this in view the amount of ammonia maywell be increased by an amount which may range as high as 50 per centabove that necessary to saponify the acids. The amount of furiuralpotassium hydrogen sulflte in the treating agent may also be varied inproportion to the other ingredients by an amount from one-third todoublethat in the tabulated formula. Also the amount of castor oil usedmay be varied or it may be omitted altogether, depending on the specificcharacter of the oil. At times it may be desirable to heat the mixtureof emulsion and .demulsifier, and also, especially when the oil is onlyslightly out and the emulsion highly stabilized, washing with brine orwater in the wash tank may expedite the demulsiflcation.

I have referred more particularly to introducing the demulsifying agentinto the flow line. from the'well, using the known or suitable means forthe purpose, but it is also possible, if preferred, to use thedemulsifying agent by a batch method, introducing it into a tank of cutoil with or without heating and with or without the addition of washwater, time being given to permit the brine to settle out after themixture has been made.

I claim:

l. A composition for demulsiiying cut oils, bottom settlings and thelike, comprising a soap and an aldehyde or ketone addition product of analkali hydrogen sulfite.

2. A composition for demulsifying cut oils, bottom s'ettlings and thelike, comprising a soap and an aldehyde addition product of an alkalihydrogen sulfite.

3. A composition iordemulsifying cut oils, bottom settlings and thelike, comprising a soap and a furfural addition product of an alkalihydrogen sulfite.

i 4. A composition for demulsiiying cut oils, bottom settlings and thelike, comprising a soap, and a water soluble aldehyde or ketone additionprodnot of an alkali hydrogen sulflte.

5. A composition for demulsiiying cut oils, bottom settlings and thelike, comprising a scan. a fixed oil and an aldehyde or ketone additionproduct of an alkali hydrogen sulilte.

6. A composition for demulsiiying cut oils, bot- 8 tom settlings and thelike, comprising an ammonia soap, and an aldehyde or ketone additionproduct oi! an alkali hydrogen sulflte.

7. A composition for demulsiiying cut oils, bottom settlings and thelike, comprising furiural potassium hydrogen sulilte and a soap.

8. A composition for demulsiiying cut oils, bottom settlings and thelike, comprising an ammonia soap oi ricinoleic acid and an aldehyde orketone addition product of an alkali hydrogen 9'. A composition fordemulsiiying cut oils, bottom settlings and the like, comprising thefollowing ingredients in substantially the proportions given: 20

Parts by volume Furiural potassium hydrogen sulflte solution 11.1Ricinoleic acid 50.4 Aq. ammonia (26 B.) l.- 8.9 25 Castor oil--- 29.6

not of an alkali hydrogen sulflte. 5

12. A process for demulsii'ying cut oils and the like comprisingtreating the oil with a soluble soap and furiural potassium hydrogensulflte.

HAROLD JAY ROBERTSON. 40

